The present invention relates generally to an apparatus for controlling a vehicle fuel pump and, in particular, to a vehicle fuel pump controller responsive to sensed vehicle conditions such as fuel demand.
As electrical and electronics components are added to vehicles, the increased electrical load is taxing the design limits of the vehicle electrical systems. Furthermore, federal and state legislation has mandated standards for reduced fuel vapor loss and fuel consumption in vehicles. Thus, automotive electrical system designers are searching for ways to increase the efficiency of the electrical components of the vehicles thereby reducing the power requirements.
The electric fuel pump consumes a relatively large amount of power from the vehicle electrical system. In order to assure a sufficiently high fuel pressure and fuel flow at the fuel injectors, fuel pumps currently used in vehicles are designed to produce a relatively constant fifty to one hundred pounds per square inch pressure with a return line and a pressure regulator to return the excess fuel to the fuel tank. Such a fuel system has two undesirable effects. One is that the returned fuel has passed through the hot environment of the engine compartment and, therefore, this heating effect increases the vapor generation in the fuel tank. The second effect is that the fuel pump consumes a relatively large amount of power, for example one hundred watts, constantly even though such full power is required only for a short time periods during start up and high rates of acceleration of the vehicle.